Illegal genetically modified (GM) rice seeds have been found in several Chinese provinces by a government investigation, according to an environment ministry official.
A joint investigation by four government departments discovered the seeds, attributing their presence to "weak management", according to the news agency Agence France-Presse (AFP).
China has allowed GM crops such as cotton, peppers, tomatoes and papayas to be grown but rice is not on this list and, as a key staple in the nation's diet, is regarded as a more sensitive crop.
In 2009 two strains of GM rice were approved for open field experiments but not commercial sale.
The website of the European Union's Rapid Alert System for Food and Feed says that European countries have found GM rice in food imported from China 115 times between 2006 and May this year.
A respected agronomist, Tong Pingya, told AFP: "China does not need this genetically modified rice, as it produces enough and even exports a bit".
There have been growing calls in China for public debate on GM organisms and clear labelling of products that contain them.